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Through the Post Box, up the Dragon's Back, down the Chute and over to the Puzzle Box. Last fall the world followed, via tweets, blogs and videos, as scientists negotiated these fancifully named landmarks of the underground system of caves known as Rising Star just outside Johannesburg, South Africa. The tight squeezes and steep drops made for difficult, dangerous work. The researchers, however, had their eyes on the prize: fossilized remains of an extinct member of the human family. Paleoanthropological fieldwork is usually done in secret, but this time the scientists posted thrilling multimedia missives along the way for all to see.

Cavers had spotted the bones in September while surveying the lesser-known caves of the famed Cradle of Humankind region. Researchers were certain the bones were important even without knowing their age and species: most of the individuals represented in the human fossil record consist of either skull fragments or bones from the neck down. This discovery had both. The association of skull and skeletal remains alone would have earned the find a prominent spot in any human origins textbook. After excavators began unearthing the bones, they realized that they had something even bigger on their hands. It was not just one individual's remains on the cave floor, as they originally thought, it was many—an entire population of early humans.